It has previously been proposed to produce a printing plate by selectively collapsing the open cell structure of a thermoplastic plate to provide relief (depression of non-printing areas), and thereby to define the non-depressed portions necessary for performing a printing operation.
It is an object of this invention to carry out the foregoing basic method in a more effective manner and at a lower cost.
It is a further object of the invention to achieve a more complete collapse of the cell structure in the areas where relief is desired, and to better define the planar difference between the raised and relief portions of the plate.